Collapsible heat shield for window of oven door

ABSTRACT

A door construction for a high temperature domestic oven having a viewing window in the door for use during cooking. Within the door is a pivoted heat shield that in one position is capable of blocking the window opening during high temperature oven operation and in another position is collapsed into a hidden position during the oven cooking operations. The weight of the shield is counterbalanced to simplify the movement of the shield.

llnite States Patent [19] won [ COLLAPSIBLE HEAT SHIELD FOR WINDOW 0F OVEN DOOR [75] Inventor: Robert A. Wolf, Louisville, Ky.

[73] Assignee: General Electric Company,

Louisville, Ky.

[22] Filed: May 6, 1974 [21] Appl. No.: 467,503

[451 Feb. 4, 197.5

3,720,196 3/1973 Barnett et a1. 126/200 Primary Examiner-Carroll B. Dority, Jr. Assistant ExaminerLarry I. Schwartz [57] ABSTRACT A door construction for a high temperature domestic 'oven having a viewing window in the door for use dur ing cooking. Within the door is a. pivoted heat shield that in one position is capable of blocking the window opening during high temperature oven operation and in another position is collapsed into a hidden position during the oven cooking operations. The weight of the shield is counterbalanced to simplify the movement of [56] References Cited the Shield 4 UNITED STATES PATENTS 3,507,267 4/1970 Lafforgue 126/200 6 Claims, 5 Drawing Figures PATENTEDFEB 41% v 3,863,619

SHEET 2 OF 2 I COLLAPSIBLE HEAT SHIELD FOR WINDOW OF OVEN DOOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a door construction having a viewing window that is provided with a movable shield for blocking the window under one set of circumstances and exposing the window for viewing under other circumstances.

2. Description of the Prior Art The present invention is particularly useful as the access door of a pyrolytic self-cleaning oven that operates at oven temperatures as high as 950F. as is described in the basic patent of Bohdan Hurko, U.S. Pat. No. 3,l21,l58, which is assigned to the same assignee as is the present invention. Windows have been available in conventional oven doors for many years. Oven users have become accustomed to the convenience of being able to observe the food through the oven door window while the food is being cooked. This avoids the necessity of opening the oven door and thereby losing some ofthe oven heat, in order to be able tojudge the degree of doneness of the food.

Special window designs are necessary for oven doors of pyrolytic self-cleaning ovens such as the use of a movable heat radiation shield or shutter which is positioned to close the window during the self-cleaning oven cycle as is taught in the patent of Howard Baughman and Kermit Keeling, Sr., US. Pat. No. 3,311,106, that is also assigned to the present assignee. The main advantages of such a heat shield are that it reduces the heat loss through thewindow passage and thereby lowers the external surface temperatures of the door, as

well as maintains a high temperature on the innermost glass pane of the window structure during the selfcleaning oven cycle so as to insure the complete removal of all food soils from the inner pane of the window by the pyrolytic process. Safety. regulations of Underwriters Laboratories, Inc.and federal safety regulating bodies are becoming more strict each year regarding the maximum allowable surface temperatures on the outer surface of the range body, especially during the high temperature self-cleaning oven cycle. Therefore, it is encumb ent upon range manufacturers to continuously refine and improve their designs to satisfy the changing needs of the public.

A principal object of the present invention is to provide an oven door with a window having a movable heat shield that is pivotally mounted in order to simplify both the mounting and operation of the shield.

A further object ofthe present invention is to provide an oven door of the class described with a collapsible shield formed by separate parts that are hinged together so as to be able to first fan out when moved to a window closing position and second to collapse when being moved to an open position for viewing through the window.

A further object ofthe present invention is to provide an oven door window of the class described with a pivoted heat shield whose weight is counterbalanced for assisting in holding the shield in either its fully open or fully closed positions.

SUMMARY OF THE INVENTION The present invention, in accordance with one form thereof, relates to a door construction provided with a viewing window having a plurality of transparent panes for sealing the window. A movable heat shield is located within the door for movement into a closed position between the transparent panes to obstruct the view. This shield is collapsible when moved to an open position out of registry with the transparent panes to permit viewing through the window. The shield is pivotally mounted within the door, and the shield includes at least two pivotal parts that allow the shield to be collapsed. Counterbalance spring means are associated with the hinge means of the shield for assisting inopening and closing the heat shield.

BRIEF DESCRIPTION OF THE DRAWINGS This invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIG. 1 is a front elevational view ofa domestic range having an oven door embodying the present invention.

FIG. 2 is a cross-sectional, side elevational view on an enlarged scale taken on the line 2-2 of FIG. I to show the interior design of the door, which the movable heat shield lowered into its open position.

FIG. 3 is an elevational view looking into the interior of the inner door liner and taken on the line 3-3 of FIG. 2 again showing the heat shield collapsed into its lowered, open position out of registry with the window opening.

FIG. 4 is an elevational view similar to that of FIG. 3 but showing the heat shield raised into its closed position covering the window opening.

FIG. 5 is a fragmentary, cross-sectional plan view taken on the line 55 of FIG. 3 showing the resilient nature of the. side handle for the heat shield, and the manner in which the handle is supported in its raised position for suspending the heat shield in its closed position of FIG. 4.

' in particular to FIG. I, there is shown for illustrative- DESCRIPTION OF THE PREFERRED EMBODIMENT I Turning now to a consideration of the drawings, and

purposes a free-standing domestic range 10 having a top cooking surface 12 with a plurality of surface heating elements 14. A baking and br'oiling oven 16 is located beneath the cooktop 12 and formed by a box-like oven liner (not shown) and a front-opening drop door 18 of the present invention. While the oven door of the present invention is shown as beinginstalled on an electric range, it will readily be apparent to those skilled in this art that the invention is not limited to use with an electric oven, for it could just as well be installed on a gas-fired oven. A backsplash 20 rises from the cooktop 12 along the back edge thereof, and it contains the necessary control components 22 for the surface heating units and oven heating units. These control components 22 are illustrated diagramatically, since they do cludes a rectangular viewing window 26 that is of reduced size as compared with the overall size of the door, and it is located generally in the top half of the door structure so that a person standing near the front of the oven may peer down into the oven through the window 26 and observe the food while it is being cooked therein.

As is best seen in FIG. 2, the oven door 18 is of generally sheet metal construction having three main elements; an outer door panel 30, an inner door liner 32, and an inner panel 34 that is supported from the inner door liner. The outer door panel 30 is of shallow pan configuration by virtue of the fact that it has a slight rearwardly facing peripheral flange 36. The inner door liner 32 is also of shallow pan configuration, and it is of mating or telescopic construction with the outer door panel 30 by virtue of the fact that it has a slight front facing peripheral flange 38 which slips into the flange 36. Suitable screw fasteners (not shown) hold the inner door liner 32 to the outer door panel 30 near the top edge of the door, while at the bottom of the door there is a tab and slot connecting relationship at 40 along most of the bottom edge of the door which prevents separation of the outer door panel from the inner door liner unless the screw fasteners at the top of the door are firstremoved.

The inner door liner 32 includes a generally rectangular raised embossment 42 on the inner side of the door which is adapted to project into a recessed front frame 44 of the oven body 16. The oven cooking cavity is formed by a box-like oven liner 46 that has an open front wall that is adapted to be closed by the oven door 18. The front of the oven liner 46 is provided with an outwardly turned front flange 48 which overlies a portion of the recessed front frame 44 by virtue of the fact that the oven liner is pulled rearwardly into the oven body 16 by tension means (not shown) such as .l-bolts or the like as is standard practice in this art.

The inner panel 34 is of shallow pan shape with a front facing peripheral flange 50, and this inner panel 34 is adapted to project into the open front of the oven liner 46, in the manner of a close fitting plug. The flattened face ofthe embossment 42 of the inner door liner 32 is formed with a largeopening or cut-outfor accommodating the flanged portion 50 of the inner panel 34 therein, thereby substantially filling the opening with the inner panel. The edge of this opening is provided with a front facing peripheral flange 54 which closely parallels the peripheral flange 50 of the inner panel 34. This peripheral flange 50 of the inner panel is shown provided with a reducing step 56 that extends completely around the inner panel so that the inner panel is of the correct size to fit closely'within the throat of the oven liner 46. Wrapped around the peripheral flange 50 near the edge thereof is a belt of gasket material 60 of thermal insulating material such as woven fiber glass or the like. This gasket 60 has an enlarged exposed edgeor bulb-like formation 62 that is adapted to seal against the front flange 48 of the oven liner 46 when the door 18 is closed. The belt gasket 60 is sandwiched between the flange 50 of the inner panel and the generally parallel flange 54 of the inner door liner 32. Spaced fastening screws 64 are threaded from inside the inner panel 34 and extend through the flange 50, the gasket 60 and the flange 54. However, it is well to realize that this type of inner panel construction and assembly allows for the expansion and contraction of the inner panel 34 during the high temperature cycle as the belt'gasket 60 serves as a resilient mounting means. For the purpose of this invention the combined inner door liner 32 and inner panel 34 may be considered as one element and may be described later as simply the inner door liner.

A sheet metal insulation guard 68 is provided to close the interior of the inner panel 34. This insulation guard 68 happens to be assembled to an inwardly facing flange 70 of the peripheral flange 54 of the inner door liner 32 as by means of screws 72. By closing off the inner panel 34, this insulation guard 68 forms a strong box-like structure which reinforces the door into a rigid structure. The interior of this box-like structure is substantially filled with thermal insulating material 74 of fiber glass or the like so as to retain much of the heat generated within the oven cavity and allow as little heat loss as possible.

Another expedient for holding down the surface temperature of the front face of the oven door is to provide natural convection air cooling within the door by creating a series of air inlet openings 76 along the bottom edge ofthe rearwardly facing flange 36 of the outer door panel 30, as well as a series of air outlet openings 78 in the top edge of the outer door panel 30. Hence, an air channel 80 is created by the spacing of the insulation guard 68 back away from the outer door panel 30. Thus, this cooling air is able to pick up some of the heat stored in the thermal insulation 74 and insulation guard 68 and serve somewhat as a heat exchanger to remove a portion of this heat by carrying it back into the kitchen. This air flow is primarily useful during the high temperature, self-cleaning oven cycle, although it also functions during normal cooking operations which makes for cool cooking as far as the outer temperature of the oven door 18 is concerned.

The general nature of this oven door 18 as described in detail above is somewhat of standard construction since it has been in production by the assignee. of the present invention, and is described in the patent of James A. White, US. Pat. No. 3,736,916, which is assignedto the present assignee. The purpose of describing the oven door 18 in.th is detail is to present the background or environment in-which the heat shield of the present invention is made to function.

The outer door panel 30is furnished with a window opening 84 over which a first transparent panel 86 of high temperature glass or the like is mounted by means of bracket members 88 which are fastened to the inner side of the outer door panel 30. A window trim frame 90 is shown positioned within the front of the opening 84 in order to improve the appearance of the window 26.

The inner door liner 32, in the form of the inner panel 34, is provided with a second window opening 94 which, also extends tothe insulation guard 68. Positioned within this second window opening 94 is a window pack subassembly 96 comprising a pair of spaced, transparent, high temperature glass panes 98 and 100 which form a thermal glazing unit. These two panes are separated by a channel-like peripheral spacer 102, and are held together by an outer channel-like frame member 104 which encircles and seals the transparent panes 98 and 100 together in a compact subassembly. This creates a dead-air space 104 between the panes to serve as a thermal insulating means to retard the conduction of heat from within the oven cooking cavity to the exterior of the window 26. As will be well understood by those skilled in this art, the thermal insulation 74 within the door encircles the window pack 96 and it is not visible after the window pack is assembled between the inner panel 34 and the insulation guard 68.

As mentioned previously, a movable heat shield 108 is considered necessary for the window of a selfcleaning oven door, where the inner oven wall temperatures may reach as high as 950F. Such a heat shield 108 is located within the cooling air channel 80. The nature of this heat shield can best be understood by referring to FIG. 4, which is a view taken from the interior of the oven door 18 looking to the inside of the inner door liner 32 and against the insulation guard 68 and out through the window pack 96 in the inner surface of the door. FIG. 4 is taken on the same line as line 3-3 of FIG. 2.

The heat shield 108 is preferably of highly reflective metal such as aluminized steel or the like and is in at least two parts. There is a first part 110 that is hinged to the insulation guard 68 by means of a lever arm 112 extending from the part 110 and a hinge pin 114 fixed to the insulation guard 68. The heat shield 108 also includes a second shield part 116 that is hinged to the first shield part 110 by means of hinge pin 118. These two shield parts 110 and 116 are collapsible with each other, as is best seen in FIG. 3, when the heat shield 108 is moved downward to its open position. These two shield parts 110 and 116 are capable of fanning out as the heat shield is moved upward to its closed position of FIG. 4 for blocking the view through the oven door window 26. I

The first shield part 110 is of generally a right triangular configuration that is adapted to cover about onehalf of the window pack 96 from one diagonal corner to the other. Adjacent the apex 117 of this right triangular configuration 110 is a lever arm extension 112 that is arranged almost perpendicular to the hypotenuse of the triangle. The hinge pin 114 is located to one side of the window at a point that is about midway of the height of the window pack 96.

The second shield part 116 is likewise of right triangular configuration, but it is arranged in an inverted manner to the first part such that the two shield parts 110 and 116 when combined into a rectangle serve to cover the rectangular window pack 96. The apex 119 of the second shield part 116 is hinged to the corner of the first shield part 110 that is opposite the apex 117 of the first shield part 110 by means of the hinge pin 118. Located along the top edge of the second shield part 116 are a pair of outwardly extending handle portions 122 and 124 which are adapted to fit through vertical slots 126 and 128 respectively in the sides of the embossment 42 of the inner door liner 32.

In order to assist in raising and lowering this collapsible heat shield 108, a counterbalance spring 130 is provided for cooperation with the lever arm 112. This counterbalance spring 130 is arranged at one side of the window pack 96, and has its lower end fixed to a post 132 as seen in FIG. 3, while its uppermost end is attached to the free end 134 of the lever arm 112. When the collapsible shield 108 is in its raised, closed position of FIG. 4, the counterbalance spring 130 is arranged to the right side of the center of the hinge pin 114. In a similar manner when the collapsible heat shield 108 is in its lowered, open position of FIG. 3,-the

counterbalance spring 130 is positioned to the left side of the center of the hinge pin 114 thereby helping to lower the heat shield and hold it in this open position.

A stop tab 134 is formed at the lowermost angular corner of the second shield part 116 for engagement beneath the apex portion 117 of the first shield part so as to limit the upward movement of the collapsible shield once the window pack 96 has been covered. Moreover, a torsion spring means 136 is positioned on the lever arm 112 for engagement against the side edge 137 of the second shield part 116, and for locking engagement beneath a notched portion 138 of the part 116to prevent the upper shield part 116 from drooping once the handle portions 122 and 124 are released by the operator.

Notice that the uppermost ends of the slots 126 and 128 are formed with an enlarged portion 140 that serves as a stop ledge that is engaged by the cooperating handle portion 122 or 124 by means of an inherent spring action causing the handle portion to slip into engagement with the ledge 140 for mechanically supporting the collapsible heat shield 108 in its raised, closed position blocking the view through the window of the oven door.

It should be understood that the oven door 18 has to be locked closed during the high temperature, selfcleaning oven operation. An oven door latch handle is shown diagrammatically as element 142 in FIG. 1. A satisfactory door latching mechanism is described in the beforementioned Baughman/lKeeling US. Pat. No. 3,31 1,106.

Another important feature is to provide an interlocking means between the heat shield 108 and the oven door latching mechanism 142 to insure that the heat shield must be closed before the oven door may be latched and the oven started on a self-cleaning cycle. This interlocking means does not form part ofthe pres ent invention, hence it' is not illustrated here for the sake of simplicity. A satisfactory interlocking feature is also described in the. Baughman/Keeling US. Pat. No. 3,311,106.

Modifications of this invention will occur to those skilled in this art. Therefore, it is to be understood that this invention is not limited to the particular embodi ments disclosed but that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.

.What is claimed as new and desired to be secured by Letters Patent of the United States is;

1. A door construction comprising-an outer panel and an inner door liner spaced inwardly therefrom, t nt a ly e sneqw nqgw aenina n s i Pane nd door liner, and transparent panes closing said window openings, a movable shield located within the door for movement into a closed position between said transparent panes to obstruct the view through said window openings, said shield being collapsible when moved to its open position out of registry with the transparent panes to permit viewing through said panes, said shield being in at least two parts, a first part hinged within the door structure and a second part hinged to the first part, said first and second shield parts overlying each.

other in said collapsed open position and being fanned out in the closed position of the shield, and counterbalance spring means associated with the hinge means of the first shield part to the door for holding the two-part shield in either its open or closed. positions.

2. A door construction as recited in claim 1 wherein the said second shield part has an outwardly extending handle portion at each side thereof, the said inner door liner having elongated slot means for receiving the handle portions therethrough whereby the collapsible shield may be operated from the inner side of the door, and releasable stop means associated with the handle portions for supporting the shield in its closed position.

3. A door construction as recited in claim 2 wherein the first shield part has an inclined edge that generally coincides with an imaginary line drawn between two opposite corners of the window openings, a lever arm extending upwardly from the first shield part at one side thereof, and hinge means fixed in the door structure and cooperating with the said lever arm for supporting this shield part for pivotal movement, the said second shield part being hinged to the said first part at the side remote from the lever arm, said second shield part also having an inclined edge generally overlying the inclined edge of the first shield part when the shield is in its closed position blocking the view through the transparent panes, the said counterbalance spring means being fixed at one end to the door structure and joined at its opposite end to the lever arm of the first shield part, the hinge means of the lever arm being a dead-center position for the counterbalance spring action.

4. A door construction as recited in claim 3 wherein the said first shield part has a configuration similar to that of a right triangle, and the said lever arm originates near the apex of the triangular first shield part, the said second shield part also having a configuration similar to that of a right triangle, the hinge means between the first and second shield parts being through the apex of the second shield part.

'5. A door construction as recited in claim 4 wherein thermal insulation means is present within the door structure to retard the flow of heat on the inner surface of the door from passing to the outer door panel, and an insulation guard plate fixed within the door structure for holding the insulation means in place, the said movable shield being hinged to the insulation guard plate, and the fixed end of the counterbalance spring means being attached to the bottom portion ofthe insulation guard plate, the shield in its collapsed open position being located beneath the said transparent panes and out of sight within the door structure.

6. A door construction as recited in claim 5 with the addition of releasable support'means on the said lever arm engageable with the second shield part when a shield is moved into its closed position to assist in supporting the said second shield part in this closed posi tion. 

1. A door construction comprising an outer panel and an inner door liner spaced inwardly therefrom, substantially alinged window openings in said panel and door liner, and transparent panes closing said window openings, a movable shield located within the door for movement into a closed position between said transparent panes to obstruct the view through said window openings, said shield being collapsible when moved to its open position out of registry with the transparent panes to permit viewing through said panes, said shield being in at least two parts, a first part hinged within the door structure and a second part hinged to the first part, said first and second shield parts overlying each other in said collapsed open position and being fanned out in the closed position of the shield, and counterbalance spring means associated with the hinge means of the first shield part to the door for holding the two-part shield in either its open or closed positions.
 2. A door construction as recited in claim 1 wherein the said second shield part has an outwardly extending handle portion at each side thereof, the said inner door liner having elongated slot means for receiving the handle portions therethrough whereby the collapsible shield may be operated from the inner side of the door, and releasable stop means associated with the handle portions for supporting the shield in its closed position.
 3. A door construction as recited in claim 2 wherein the first shield part has an inclined edge that generally coincides with an imaginary line drawn between two opposite corners of the window openings, a lever arm extending upwardly from the first shield part at one side thereof, and hinge means fixed in the door structure and cooperating with the said lever arm for supporting this shield part for pivotal movement, the said second shield part being hinged to the said first part at the side remote from the lever arm, said second shield part also having an inclined edge generally overlying the inclined edge of the first shield part when the shield is in its closed position blocking the view through the transparent panes, the said counterbalance spring means being fixed at one end to the door structure and joined at its opposite end to the lever arm of the first shield part, the hinge means of the lever arm being a dead-center position for the counterbalance spring action.
 4. A door construction as recited in claim 3 wherein the said first shield part has a configuration similar to that of a right triangle, and the said lever arm originates near the apex of the triangular first shield part, the said second shield part also having a configuration similar to that of a right triangle, the hinge means between the first and second shield parts being through the apex of the second shield part.
 5. A door construction as recited in claim 4 wherein thermal insulation means is present within the door structure to retard the flow of heat on the inner surface of the door from passing to the outer door panel, and an insulation guard plate fixed within the door structure for holding the insulation means in place, the said movable shield being hinged to the insulation guard plate, and the fixed end of the counterbalance spring means being attached to the bottom portion of the insulation guard plate, the shield in its collapsed open position being located beneath the said transparent panes and out of sight within the door structure.
 6. A door construction As recited in claim 5 with the addition of releasable support means on the said lever arm engageable with the second shield part when a shield is moved into its closed position to assist in supporting the said second shield part in this closed position. 